Question

sin12'-sin48'/1-2cos^2 54'

Answer 1

$frac{sin12-sin48}{1-2cos^254}=frac{2cos30sin(-18)}{1-(1+cos108)}=\ =frac{-2*frac{sqrt{3}}{2}sin18}{cos(90+18)}=frac{-sqrt{3}sin18}{-sin18}=sqrt{3}$